problem with for loop

Hi I have problem with for loop ; when i run this code,i think probably one loop does not stop and matlab stays on busy mode i want to understand where is the problem in my program (i attached all functions to this question)

a part of code:

   for i=2:length(x)-1 
    for j=2:length(y)-1
        z = 0:0.1:1;
    for zindex=1:11

    for nindex = [1,10] 
     u(i, j, 2, zindex+1, nindex)= G(z(zindex), nindex)/ro(z(zindex), nindex)^2*dt^2*((1/deltar^2)*(u(i+1,j,1)-2*u(i,j,1)+u(i-1,j,1))...
                +(1/(ri*2*deltar))*(u(i+1,j,1)-u(i-1,j,1))+(1/deltaz^2)*(u(i,j+1,1)-2*u(i,j,1)+u(i,j-1,1))-(1/ri^2)*(u(i,j,1))) + 2*u(i,j,1) - u(i,j,1);
    end
    end
    end
end
for n=2:length(t)-1
    for i=2:length(x)-1
        for j=2:length(y)-1
              z = 0:0.1:1;
    for zindex=1:11
    for nindex = [1,10] 
            u(i,j,n+1,zindex+1,nindex)= G(z(zindex), nindex)/ro(z(zindex), nindex)^2*dt^2*((1/deltar^2)*(u(i+1,j,n)-2*u(i,j,n)+u(i-1,j,n))...
                +(1/(ri*2*deltar))*(u(i+1,j,n)-u(i-1,j,n))+(1/deltaz^2)*(u(i,j+1,n)-2*u(i,j,n)+u(i,j-1,n))-(1/ri^2)*(u(i,j,n))) + 2*u(i,j,n) - u(i,j,n-1);
    end
    end
        end
    end
end

[KL]

Learn how to use debugging: https://www.mathworks.com/help/matlab/matlab_prog/debugging-process-and-features.html

[KSSV]

Try to take loop indices as output's on the screen.....and check at what indices it is taking much time...or run a profiler for small indices.